ARRT Computed Tomography (CT) Certification Examination — Questions and Answers

Question 1: On axial CT at the level of the umbilicus, which abdominal wall muscle is most lateral?

Internal oblique
External oblique (Correct answer)
Transversus abdominis
Rectus abdominis

Correct answer: External oblique

The external oblique is the most superficial and lateral of the flat abdominal wall muscles, lying outside the internal oblique.

Question 2: For a CT scan of the spine performed to evaluate for disk herniation, which reconstruction kernel is preferred?

Ultra-high-resolution kernel
Lung (high-frequency) kernel
Bone (high-frequency) kernel
Standard soft tissue kernel (Correct answer)

Correct answer: Standard soft tissue kernel

A standard or intermediate soft tissue kernel is preferred for disk and neural structure evaluation, reducing noise while preserving relevant detail.

Question 3: In CT, 'effective mAs' (mAs/pitch) is important because:

It remains constant regardless of pitch, maintaining image noise consistency (Correct answer)
It sets the rotation time only
It controls the display window
It determines the field of view

Correct answer: It remains constant regardless of pitch, maintaining image noise consistency

Effective mAs = mAs ÷ pitch; keeping this constant as pitch changes maintains consistent image noise regardless of table speed.

Question 4: During a CT-guided biopsy procedure, which measure BEST reduces radiation exposure to the interventional CT technologist?

Using fluoroscopy-like CT intermittently and stepping back during exposures (Correct answer)
Wearing a lead apron only when the patient is being positioned
Reducing tube current to zero between acquisitions
Standing at the gantry opening throughout the procedure

Correct answer: Using fluoroscopy-like CT intermittently and stepping back during exposures

Intermittent CT fluoroscopy combined with stepping away from the gantry during exposures significantly reduces occupational dose during interventional procedures.

Question 5: A CT technologist completes a 3-credit online module from an ARRT-approved sponsor. How should this be recorded?

Only if the module includes a hands-on component
As Category B self-study credit
It counts only if completed before the renewal year begins
As 3 Category A CE credits (Correct answer)

Correct answer: As 3 Category A CE credits

Online modules from ARRT-approved sponsors qualify as Category A CE credits and count toward the 24-credit renewal requirement.

Question 6: For a CT of the paranasal sinuses ordered to guide functional endoscopic sinus surgery (FESS), which plane is most critical for the surgeon?

Coronal plane (Correct answer)
Oblique plane
Sagittal plane
Axial plane

Correct answer: Coronal plane

The coronal plane directly depicts the ostiomeatal complex, sinus drainage pathways, and the relationship to the orbit and skull base — essential for FESS planning.

Question 7: A patient receiving oxygen via nasal cannula at 2 L/min needs a portable chest X-ray. The technologist should:

Switch the patient to a face mask before imaging
Leave the oxygen in place and proceed with the exam (Correct answer)
Discontinue oxygen as it interferes with imaging
Remove the oxygen cannula during the exposure

Correct answer: Leave the oxygen in place and proceed with the exam

Supplemental oxygen should not be interrupted; nasal cannulas do not significantly affect image quality and the patient's oxygenation status must be maintained.

Question 8: What are the principles of mission command?

Technology, firepower, logistics
Speed, power, aggression
Competence, mutual trust, shared understanding, commander's intent (Correct answer)
Rank, authority, obedience

Correct answer: Competence, mutual trust, shared understanding, commander's intent

Mission command empowers subordinates through trust, shared understanding of the commander's intent, and disciplined initiative.

Question 9: On axial CT of the orbit, which extraocular muscle is located at the medial wall of the orbit?

Superior rectus
Medial rectus (Correct answer)
Superior oblique
Inferior oblique

Correct answer: Medial rectus

The medial rectus muscle runs along the medial orbital wall and is the most commonly enlarged muscle in thyroid eye disease.

Question 10: Which of the following activities can count toward the continuing education credits for ARRT CT certification?

Publishing a research article in a professional journal
Completing a patient care workshop
All of the above (Correct answer)
Attending an industry conference

Correct answer: All of the above

ARRT accepts a wide range of activities for continuing education (CE) credits, provided they are relevant to the radiologic sciences. This includes attending industry conferences, participating in patient care workshops, and even publishing research articles in professional journals. The goal is to encourage diverse learning that enhances professional practice.

Question 11: Which regulatory body sets the annual occupational effective dose limit of 50 mSv in the United States?

CDC
ARRT
FDA
NRC and Agreement States (Correct answer)

Correct answer: NRC and Agreement States

The Nuclear Regulatory Commission (NRC) and Agreement State regulations set the 50 mSv/year occupational effective dose limit (10 CFR 20).

Question 12: A radiologic technologist notices that CT images of the liver appear uniformly noisy despite using standard mAs. The MOST appropriate first corrective action is:

Reduce the reconstruction FOV by 50%
Switch to a narrower window width for display
Double the mAs for the repeat scan immediately
Verify that the correct reconstruction kernel and algorithm are applied (Correct answer)

Correct answer: Verify that the correct reconstruction kernel and algorithm are applied

Verifying protocol settings (kernel, algorithm, slice thickness) first ensures the source of apparent noise is identified before unnecessarily increasing dose.

Question 13: CT colonoscopy (virtual colonoscopy) relies on which post-processing technique to create a simulated fly-through view of the colon lumen?

Volume rendering with endoluminal navigation (Correct answer)
Maximum intensity projection
Minimum intensity projection
Subtraction imaging

Correct answer: Volume rendering with endoluminal navigation

Volume rendering with endoluminal navigation uses the air-distended colon as a flight path, generating a simulated colonoscopic perspective of the mucosal surface.

Question 14: Which approach is used in a split-bolus IV contrast protocol for CT of the abdomen?

A single rapid bolus followed by immediate scanning
Two separate injections given at different time points before scanning (Correct answer)
Saline flush only with no contrast
Contrast injected into the portal vein directly

Correct answer: Two separate injections given at different time points before scanning

The split-bolus technique delivers two injections at different time intervals so a single scan pass captures both nephrographic and excretory phases simultaneously.

Question 15: A patient taking metformin for type 2 diabetes is receiving IV iodinated contrast. Per ACR guidelines, when should metformin be withheld after contrast administration in a patient with normal renal function?

Withhold only if the patient has an allergic reaction
Withhold for 72 hours regardless of renal function
Withhold for 24 hours before and after the exam
It does not need to be withheld in patients with normal renal function (Correct answer)

Correct answer: It does not need to be withheld in patients with normal renal function

ACR guidelines state that patients with normal renal function (eGFR ≥ 30) receiving IV contrast do not need to withhold metformin.

Question 16: The inverse square law states that radiation intensity is related to distance by which relationship?

Intensity is directly proportional to distance
Intensity is inversely proportional to the square of the distance (Correct answer)
Intensity decreases linearly with distance
Intensity is inversely proportional to the cube of the distance

Correct answer: Intensity is inversely proportional to the square of the distance

The inverse square law: I ∝ 1/d², meaning doubling the distance from the source reduces intensity to one-quarter of its original value.

Question 17: How does earning ARRT CT certification typically affect a technologist's hourly wage compared to uncertified peers?

It reduces wages due to higher employer expectations
It typically results in a 5–15% higher hourly wage (Correct answer)
It guarantees a doubling of salary
It has no measurable impact on wages

Correct answer: It typically results in a 5–15% higher hourly wage

Studies and salary surveys consistently show certified CT technologists earn 5–15% more per hour than non-certified counterparts.

Question 18: CT calcium scoring of the coronary arteries uses which post-processing method to quantify calcification?

Subtraction of non-contrast from contrast images
Agatston scoring based on lesion area and peak Hounsfield unit density (Correct answer)
MIP projection over the cardiac cycle
Volume rendering with opacity mapping

Correct answer: Agatston scoring based on lesion area and peak Hounsfield unit density

Agatston scoring multiplies the area of each calcified lesion by a density factor based on peak HU (1–4 scale), then sums all lesions to yield the total calcium score.

Question 19: What is the primary purpose of selecting a small reconstruction FOV (field of view) during CT image reconstruction?

To increase the pixel size for better soft tissue contrast
To decrease image noise
To reduce patient dose
To improve spatial resolution by sampling more detail per pixel (Correct answer)

Correct answer: To improve spatial resolution by sampling more detail per pixel

A smaller reconstruction FOV divides the imaged area into the same matrix of pixels, resulting in smaller pixel size and therefore higher spatial resolution of the region of interest.

Question 20: Which CT feature of a pulmonary nodule is most associated with malignancy?

Smooth well-defined margins
Spiculated margins with pleural tethering (Correct answer)
Stippled central calcification
Laminated calcification pattern

Correct answer: Spiculated margins with pleural tethering

Spiculated margins with pleural tethering are high-risk features indicating likely malignant invasion of adjacent lung parenchyma.

Question 21: For a radiologic technologist considering subspecialty practice, which statement about ARRT CT certification scope is most accurate?

CT certification is equivalent to a fellowship in CT radiology
CT certification covers interventional radiology procedures as well
CT certification validates technical performance skills, not image interpretation or diagnosis (Correct answer)
CT certification qualifies technologists to independently interpret CT scans

Correct answer: CT certification validates technical performance skills, not image interpretation or diagnosis

ARRT CT certification validates technical performance and patient care competencies; image interpretation and diagnosis remain within the radiologist's scope.

Question 22: In a CT perfusion study of the brain, which parameter measures the volume of blood in a given unit of brain tissue?

Time to peak (TTP)
Cerebral blood flow (CBF)
Mean transit time (MTT)
Cerebral blood volume (CBV) (Correct answer)

Correct answer: Cerebral blood volume (CBV)

Cerebral blood volume (CBV) represents the total volume of blood within a defined brain tissue volume, measured in mL/100g.

Question 23: A CT scan protocol using 'prospective ECG gating' for cardiac imaging acquires data only during which part of the cardiac cycle?

Only during a pre-selected phase of diastole (Correct answer)
Only during systole
During both systole and diastole equally
Throughout the entire R-R interval

Correct answer: Only during a pre-selected phase of diastole

Prospective ECG gating triggers X-ray exposure only during a selected quiescent diastolic window, substantially reducing radiation dose compared to retrospective gating.

Question 24: Which ACR-recommended CT quality control test should be performed if visual image artifacts are noted during clinical scanning?

Reduce the scan FOV and repeat without QC evaluation
Switch to a different reconstruction kernel and continue scanning
Immediately repeat the patient scan at higher mAs
Perform artifact analysis using an appropriate phantom and document findings before continuing clinical use (Correct answer)

Correct answer: Perform artifact analysis using an appropriate phantom and document findings before continuing clinical use

When clinical artifacts are observed, ACR guidelines require phantom-based artifact analysis and documentation before continuing patient scanning to ensure diagnostic image quality.

Question 25: Which phantom is used to measure CTDI100 according to the standard FDA/IEC protocol?

A 32 cm diameter cylindrical PMMA phantom for head and a 16 cm phantom for body
A 20 cm sphere filled with tissue-equivalent material
A 16 cm diameter PMMA phantom for head and a 32 cm phantom for body (Correct answer)
A water-filled anthropomorphic phantom

Correct answer: A 16 cm diameter PMMA phantom for head and a 32 cm phantom for body

The FDA/IEC protocol uses a 16 cm PMMA phantom for head measurements and a 32 cm phantom for body measurements to derive CTDI100.

Question 26: For a CT coronary angiography (CCTA) protocol, which heart rate range is generally ideal to minimize motion artifact?

<65 bpm (Correct answer)
>100 bpm
65–80 bpm
80–100 bpm

Correct answer: <65 bpm

Heart rates below 65 bpm allow longer diastolic rest periods, reducing cardiac motion artifact during CCTA acquisition.

Question 27: Within what timeframe must newly certified CT technologists complete their first renewal cycle?

When their primary registration expires (Correct answer)
One year from certification date
Three years from certification date
Two years from certification date

Correct answer: When their primary registration expires

Post-primary certification renewal is typically aligned with the technologist's primary registration renewal date, not a separate independent cycle.

Question 28: What is a Hounsfield unit?

A unit of image resolution
A measure of scan speed
A unit of radiation dose
A quantitative measurement of tissue density on CT images (Correct answer)

Correct answer: A quantitative measurement of tissue density on CT images

Hounsfield units (HU) measure tissue density on CT, with water at 0 HU, air at -1000 HU, and dense bone at +1000 HU or higher.

Question 29: Which factor is evaluated by the modulation transfer function (MTF) in CT quality control?

CT number linearity
Low-contrast detectability
High-contrast spatial resolution (Correct answer)
Image noise levels

Correct answer: High-contrast spatial resolution

The MTF describes how faithfully the CT system reproduces spatial detail, directly measuring high-contrast spatial resolution performance.

Question 30: The purpose of a body mechanics principle such as 'keeping the load close to the body' when lifting a patient is to:

Protect the patient from falling
Increase the speed of the transfer
Reduce strain on the lumbar spine by minimizing torque (Correct answer)
Maintain proper sterile field distance

Correct answer: Reduce strain on the lumbar spine by minimizing torque

Keeping a load close to the body reduces the moment arm and therefore the torque placed on the lumbar vertebrae, preventing injury.

Question 31: Aliasing artifacts in CT, which appear as fine streaks or Moiré patterns, are caused by which factor?

Excessive patient size
Insufficient detector sampling (Correct answer)
High kVp settings
Incorrect table speed

Correct answer: Insufficient detector sampling

Aliasing artifacts occur when the object being imaged contains spatial frequencies higher than the detector sampling rate can capture, per the Nyquist theorem.

Question 32: What is the purpose of contrast media in CT scans?

To speed up the scan
To reduce radiation dose
To make the patient comfortable
To enhance the visibility of specific structures and pathology (Correct answer)

Correct answer: To enhance the visibility of specific structures and pathology

Contrast media (dye) enhances the visibility of blood vessels, organs, and abnormalities by changing how X-rays interact with specific tissues.

Question 33: What does informed consent require?

Family approval only
Explaining the procedure, risks, benefits, and alternatives to the patient (Correct answer)
Verbal agreement only
Getting any signature on a form

Correct answer: Explaining the procedure, risks, benefits, and alternatives to the patient

Informed consent requires that patients understand the proposed procedure, its risks and benefits, alternatives, and have the opportunity to ask questions before agreeing.

Question 34: How does ARRT CT certification support a technologist's participation in quality improvement initiatives within their department?

It disqualifies technologists from serving on quality committees
It provides the advanced protocol and dose optimization knowledge needed to contribute meaningfully to QI projects (Correct answer)
It only applies to patient scheduling improvements
It transfers QI responsibilities entirely to the radiologist

Correct answer: It provides the advanced protocol and dose optimization knowledge needed to contribute meaningfully to QI projects

The depth of CT knowledge required for ARRT certification equips technologists to identify protocol inefficiencies, dose issues, and image quality problems in QI settings.

Question 35: The spatial frequency at which the MTF falls to 10% is commonly used to define:

The noise power spectrum peak
The detective quantum efficiency (DQE)
The optimal reconstruction FOV
The limiting spatial resolution of the CT system (Correct answer)

Correct answer: The limiting spatial resolution of the CT system

MTF10% represents the highest spatial frequency the system can transfer with 10% modulation, effectively defining the limiting resolution.

Question 36: Which employment sector has seen the fastest growth in demand for ARRT CT-certified technologists in recent years?

Dental radiography offices
Outpatient and freestanding imaging centers (Correct answer)
Film-based radiology departments
Veterinary imaging clinics

Correct answer: Outpatient and freestanding imaging centers

The rapid expansion of outpatient and freestanding imaging centers has driven increased demand for ARRT CT-certified technologists outside traditional hospital settings.

Question 37: An automatic exposure control (AEC) system in CT adjusts which parameter in real time?

Tube current (mA) based on patient attenuation (Correct answer)
Reconstruction kernel
Detector row width
Gantry rotation speed

Correct answer: Tube current (mA) based on patient attenuation

CT AEC (tube current modulation) automatically adjusts mA based on patient size and attenuation to maintain consistent image quality at optimal dose.

Question 38: The annual occupational dose limit for the lens of the eye, as updated by NCRP Report No. 172, is:

5 mSv
50 mSv
20 mSv (Correct answer)
150 mSv

Correct answer: 20 mSv

NCRP Report No. 172 (2016) lowered the recommended annual occupational lens dose limit to 20 mSv/year averaged over 5 years, consistent with ICRP 103.

Question 39: Which technique is most commonly used to reduce metal artifact in CT imaging of patients with hip prostheses?

Using a smaller FOV
Increasing slice thickness
Metal artifact reduction (MAR) software (Correct answer)
Decreasing kVp

Correct answer: Metal artifact reduction (MAR) software

Metal artifact reduction (MAR) algorithms replace corrupted projection data near metal with interpolated data, significantly reducing streaking artifacts.

Question 40: What is the first step in the ARRT CT certification process?

Submit an online application through the ARRT portal (Correct answer)
Complete the required clinical competencies
Obtain a recommendation letter from an employer
Schedule the CT certification exam

Correct answer: Submit an online application through the ARRT portal

The initial step in the ARRT CT certification process, after meeting all prerequisites, is to formally apply. This is done by submitting an online application through the official ARRT website portal. This application initiates the eligibility review and allows candidates to proceed with scheduling their exam.

Question 41: Quantum (photon) noise in CT images is most visible under which conditions?

Low mAs or large patient size (Correct answer)
Fast pitch and narrow FOV
High kVp and wide window
High mAs and thin slices

Correct answer: Low mAs or large patient size

Quantum noise increases when fewer photons reach the detectors, which occurs with low mAs settings or when X-rays are attenuated by a large patient.

Question 42: A candidate fails the ARRT CT examination. What is the minimum waiting period before their first retake?

1 year
2 weeks
6 months
3 months (Correct answer)

Correct answer: 3 months

ARRT requires a 3-month waiting period between examination attempts to allow candidates time for remediation.

Question 43: What is preventive maintenance?

Regular scheduled maintenance to prevent equipment failure (Correct answer)
Cleaning only
Fixing equipment after it breaks
Replacing all equipment annually

Correct answer: Regular scheduled maintenance to prevent equipment failure

Preventive maintenance involves regular, scheduled inspections and servicing to prevent unexpected breakdowns and extend equipment life.

Question 44: What does 'afterglow' (or 'ghosting') in CT solid-state detectors cause?

Reduced spatial resolution due to detector cross-talk
Increased image noise due to photon starvation
Ring artifacts from a single failed detector channel
Residual signal carried over from prior projections, causing streak artifacts (Correct answer)

Correct answer: Residual signal carried over from prior projections, causing streak artifacts

Afterglow occurs when scintillator crystals continue to emit light after X-ray exposure ends, carrying residual signal into subsequent projections and causing streak or shading artifacts.

Question 45: In multi-detector CT (MDCT), increasing the number of detector rows primarily allows:

Elimination of pitch requirements
Higher kVp settings
Reduced x-ray tube heat loading per scan
Simultaneous acquisition of more slices per rotation, improving z-axis coverage speed (Correct answer)

Correct answer: Simultaneous acquisition of more slices per rotation, improving z-axis coverage speed

More detector rows mean more slice data acquired per rotation, covering a larger anatomical volume per gantry revolution and reducing scan time.

Question 46: What is homeostasis?

A type of cell division
The body's ability to maintain stable internal conditions (Correct answer)
An organ system
A disease state

Correct answer: The body's ability to maintain stable internal conditions

Homeostasis is the body's dynamic process of maintaining stable internal conditions (temperature, pH, blood sugar) despite external changes.

Question 47: The windmill artifact seen in helical CT is most commonly associated with which acquisition parameter?

Low kVp
Small reconstruction FOV
High pitch values (Correct answer)
Large detector collimation

Correct answer: High pitch values

Windmill artifacts appear as alternating dark and bright streaks rotating around structures and are caused by the under-sampling that occurs at high pitch values.

Question 48: How many continuing education credits must ARRT-registered CT technologists earn during each 2-year renewal cycle?

36 credits
48 credits
24 credits (Correct answer)
12 credits

Correct answer: 24 credits

ARRT requires 24 Category A continuing education credits per 2-year renewal cycle for registered technologists.

Question 49: Which statement best describes an isotropic voxel in CT imaging?

A voxel that contains only one tissue type
A voxel with maximum attenuation value
A voxel reconstructed using iterative algorithms
A voxel with equal dimensions in x, y, and z axes (Correct answer)

Correct answer: A voxel with equal dimensions in x, y, and z axes

Isotropic voxels have equal measurements in all three spatial dimensions, enabling high-quality MPR and 3D reconstructions in any plane without stair-step degradation.

Question 50: Which of the following scenarios would trigger ARRT's mandatory ethics disclosure requirement?

A technologist works per diem at multiple facilities
A technologist changes their legal name
A technologist receives a civil traffic violation
A technologist is convicted of healthcare fraud (Correct answer)

Correct answer: A technologist is convicted of healthcare fraud

ARRT's Standards of Ethics require self-disclosure of criminal convictions, including healthcare fraud, within 30 days of the conviction.

Question 51: What is the recommended frequency for performing a full CT equipment performance evaluation by a qualified medical physicist?

Annually (Correct answer)
Every five years
Weekly
Daily

Correct answer: Annually

ACR and AAPM guidelines recommend a comprehensive CT performance evaluation by a qualified medical physicist at least annually.

Question 52: How many total attempts does ARRT allow a candidate to take the CT certification examination?

2 attempts
Unlimited attempts
3 attempts (Correct answer)
5 attempts

Correct answer: 3 attempts

ARRT limits candidates to 3 total attempts to pass each post-primary examination, including CT.

Question 53: Windowing in CT (setting window width and level) affects:

The spatial resolution of the image
The actual CT numbers in the reconstructed data
Radiation dose to the patient
Only the display of contrast by mapping HU values to gray shades (Correct answer)

Correct answer: Only the display of contrast by mapping HU values to gray shades

Windowing is a display operation that maps selected HU ranges to the visible gray scale; it does not alter the underlying image data.

Question 54: What is the correct order for donning PPE?

Any order is acceptable
Mask, gloves, gown, eye protection
Gloves, gown, mask, eye protection
Gown, mask, eye protection, gloves (Correct answer)

Correct answer: Gown, mask, eye protection, gloves

The correct donning sequence is gown first, then mask/respirator, eye protection/face shield, and gloves last. This prevents contamination during application.

Question 55: A standard high-resolution CT (HRCT) chest protocol uses which reconstruction approach to evaluate interstitial lung disease?

Thick slices with soft tissue kernel
Thin slices with soft tissue kernel
Thin slices with high-frequency (sharp) kernel (Correct answer)
Thick slices with bone kernel

Correct answer: Thin slices with high-frequency (sharp) kernel

HRCT uses thin slices (≤1.5 mm) with a high-spatial-frequency kernel to maximize edge detail of lung parenchyma and airways.

Question 56: Which statement best describes the principle of informed consent?

Consent is implied once the patient enters the radiology department
The patient must be given a full explanation of the procedure, risks, benefits, and alternatives before voluntarily agreeing (Correct answer)
The patient signs a form without needing a full explanation of the procedure
Consent may be obtained by any staff member regardless of their role

Correct answer: The patient must be given a full explanation of the procedure, risks, benefits, and alternatives before voluntarily agreeing

Informed consent requires full disclosure of the procedure, risks, benefits, and alternatives so the patient can make a voluntary, knowledgeable decision.

Question 57: Which factor primarily determines the z-axis (longitudinal) resolution in a multislice CT scanner?

Detector row width (Correct answer)
Gantry rotation speed
kVp setting
Reconstruction matrix size

Correct answer: Detector row width

Z-axis resolution is primarily determined by detector row width (collimation), which defines slice thickness in the longitudinal direction.

Question 58: Regarding the ARRT CT eligibility requirement for moral character, which of the following is TRUE?

Moral character is only evaluated after the examination is passed
ARRT does not have a moral character requirement for post-primary certifications
Candidates must attest to meeting ARRT Standards of Ethics at the time of application (Correct answer)
Moral character requirements apply only to new graduates, not experienced technologists

Correct answer: Candidates must attest to meeting ARRT Standards of Ethics at the time of application

All ARRT applicants must attest to meeting the Standards of Ethics, including moral character, as part of the application process.

Question 59: Aliasing artifacts in CT most commonly occur due to:

Overuse of iterative reconstruction
Insufficient angular sampling of projection data (undersampling) (Correct answer)
High patient body mass index
Calibration errors in the slip ring

Correct answer: Insufficient angular sampling of projection data (undersampling)

Aliasing arises when the sampling rate of projection views is too low to accurately represent fine detail, producing Moiré-like or streak patterns.

Question 60: What does a noise index (NI) setting in automatic tube current modulation (ATCM) control?

The target image noise level that drives mA adjustments (Correct answer)
The amount of bowtie filter attenuation
The maximum allowed kVp during the scan
The number of reconstruction iterations applied

Correct answer: The target image noise level that drives mA adjustments

The noise index defines the target standard deviation of image noise; ATCM raises or lowers mA to achieve this noise target based on patient attenuation.

Question 61: Which statement BEST describes the relationship between CT noise and mAs?

Noise is inversely proportional to mAs
Noise is unaffected by mAs changes
Noise is directly proportional to mAs
Noise is proportional to 1/√mAs (Correct answer)

Correct answer: Noise is proportional to 1/√mAs

CT noise follows Poisson statistics; doubling mAs quadruples photons but only reduces noise by a factor of √2, making noise proportional to 1/√mAs.

Question 62: Partial volume averaging artifacts in CT are best reduced by which acquisition parameter adjustment?

Increasing mAs
Widening the display window
Increasing kVp
Using a thinner slice thickness (Correct answer)

Correct answer: Using a thinner slice thickness

Thinner slices reduce partial volume averaging by ensuring each voxel contains tissue from a smaller volume, improving accuracy of CT numbers.

Question 63: What are standard precautions in healthcare?

Hand washing after patient contact only
Only wearing gloves for known infections
Using masks during surgery only
Treating all blood and body fluids as potentially infectious (Correct answer)

Correct answer: Treating all blood and body fluids as potentially infectious

Standard precautions assume all blood and body fluids are potentially infectious, requiring consistent use of barriers (gloves, gowns, masks) and hand hygiene for all patient interactions.

Question 64: Which artifact appears as a dark band between two high-density objects on a CT image and is caused by beam hardening?

Moiré artifact
Ring artifact
Windmill artifact
Shadowing or 'dark band' artifact (Correct answer)

Correct answer: Shadowing or 'dark band' artifact

Dark bands (also called 'shadowing' or 'cupping' between dense objects) arise from extreme beam hardening where few low-energy photons survive to reach the detector between two dense structures.

Question 65: Curved planar reformation (CPR) in CT is most useful for:

Straightening and displaying tortuous structures such as vessels or the spine along their entire length (Correct answer)
Generating endoscopic views of hollow organs
Creating color-coded perfusion maps
Subtracting bone from CT angiography images

Correct answer: Straightening and displaying tortuous structures such as vessels or the spine along their entire length

CPR follows a user-defined curved path through the volume dataset to display a tortuous structure in a single unfolded plane, useful for coronary arteries or the aorta.

Question 66: Which of the following best describes a 'dual-phase' liver CT protocol?

Portal venous and delayed phases only
Non-contrast and delayed phases only
Arterial and portal venous phases (Correct answer)
Non-contrast and arterial phases only

Correct answer: Arterial and portal venous phases

A dual-phase liver protocol acquires images in both the hepatic arterial phase and the portal venous phase to characterize liver lesions.

Question 67: During a multi-phase CT liver protocol (non-contrast, arterial, portal venous, delayed), which action BEST reduces cumulative patient dose?

Increase slice thickness per phase to reduce total acquisitions
Eliminate phases not essential for the clinical indication and use dose modulation for each phase (Correct answer)
Increase kVp for each phase to reduce noise
Use the maximum mAs for all phases to guarantee image quality

Correct answer: Eliminate phases not essential for the clinical indication and use dose modulation for each phase

Eliminating unnecessary scan phases and applying tube current modulation to each remaining phase are the most effective strategies to reduce cumulative multi-phase CT dose.

Question 68: In CT, the term 'pitch' for single-slice CT is calculated as:

kVp / mAs
Table speed / gantry rotation time
Detector width / field of view
Table feed per rotation / slice thickness (Correct answer)

Correct answer: Table feed per rotation / slice thickness

Pitch = table feed per 360° rotation divided by the nominal slice thickness; a pitch >1 means gaps exist between consecutive slices.

Question 69: What type of artifact appears as bright or dark streaks radiating from high-density objects like metal implants in CT images?

Ring artifact
Motion artifact
Beam hardening artifact (Correct answer)
Partial volume artifact

Correct answer: Beam hardening artifact

Beam hardening artifacts appear as streaks or dark bands radiating from dense metallic objects because lower-energy photons are preferentially absorbed.

Question 70: When using bolus tracking for a contrast-enhanced CT aorta study, where is the region of interest (ROI) typically placed to trigger scanning?

Descending aorta at the level of the diaphragm or ascending aorta (Correct answer)
Left ventricle
Pulmonary artery
Inferior vena cava

Correct answer: Descending aorta at the level of the diaphragm or ascending aorta

For aortic CTA, the ROI for bolus tracking is placed in the aorta (ascending or at the diaphragm level) to trigger acquisition when contrast reaches the threshold HU.

Question 71: What are the four basic tissue types in the human body?

Epithelial, connective, muscle, and nervous (Correct answer)
Skin, bone, blood, and fat
Brain, heart, lung, and liver
Smooth, rough, dense, and loose

Correct answer: Epithelial, connective, muscle, and nervous

The four fundamental tissue types are epithelial (covering/lining), connective (support/connection), muscle (movement), and nervous (communication/control).

Question 72: A radiologic technologist holds R.T.(R)(CT) credentials. What do the letters in parentheses each represent?

(R) = primary ARRT registration in Radiography; (CT) = post-primary CT certification (Correct answer)
(R) = Radiology degree; (CT) = computed tomography license
(R) = residency completed; (CT) = computed tomography board
(R) = state registration; (CT) = federal CT permit

Correct answer: (R) = primary ARRT registration in Radiography; (CT) = post-primary CT certification

R.T.(R) denotes primary ARRT registration in Radiography, and (CT) denotes the additional post-primary CT certification earned.

Question 73: A CT technologist completes 30 Category A credits in one renewal cycle. How many, if any, credits can be carried over to the next cycle?

6 credits can be carried over
All excess credits carry over automatically
12 credits can be carried over
0 credits — no carryover is allowed (Correct answer)

Correct answer: 0 credits — no carryover is allowed

ARRT does not allow Category A CE credits to be carried over from one renewal cycle to the next.

Question 74: What is the difference between arteries and veins?

They carry the same blood in the same direction
Arteries carry blood away from the heart; veins carry blood toward the heart (Correct answer)
Veins are thicker than arteries
Arteries are only in the lungs

Correct answer: Arteries carry blood away from the heart; veins carry blood toward the heart

Arteries carry blood away from the heart (usually oxygenated) while veins carry blood toward the heart (usually deoxygenated). Arteries have thicker walls to handle higher pressure.

Question 75: What is the function of red blood cells?

To clot blood
To fight infection
To transport oxygen from lungs to tissues and CO2 back (Correct answer)
To produce hormones

Correct answer: To transport oxygen from lungs to tissues and CO2 back

Red blood cells (erythrocytes) contain hemoglobin that binds oxygen in the lungs and delivers it to tissues, then carries carbon dioxide back for exhalation.

Question 76: What does OPSEC stand for?

Operational Section
Optional Security
Operating System Executive
Operations Security (Correct answer)

Correct answer: Operations Security

OPSEC protects critical information from adversaries by identifying and safeguarding sensitive data.

Question 77: For a CT abdomen/pelvis with IV contrast, what is the typical scan delay after contrast injection to capture the nephrographic phase of the kidneys?

10–15 seconds
25–35 seconds
80–120 seconds (Correct answer)
3–5 minutes

Correct answer: 80–120 seconds

The nephrographic phase occurs approximately 80–120 seconds post-injection, when the renal cortex and medulla enhance uniformly, optimizing detection of renal masses.

Question 78: What does the term 'detector efficiency' refer to in CT scanner performance?

The number of detector rows in the system
The speed at which the gantry rotates
The FOV coverage per rotation
The ability of detectors to capture and convert X-ray photons into usable signal (Correct answer)

Correct answer: The ability of detectors to capture and convert X-ray photons into usable signal

Detector efficiency describes how effectively CT detectors absorb incident X-ray photons and convert them into electrical signal, directly affecting image quality and dose.

Question 79: A starburst pattern of streaks emanating from the edge of the patient's shoulders during a neck CT is most likely caused by:

Detector malfunction
Gantry tilt error
Incorrect windowing
Beam hardening from bone and soft tissue interfaces (Correct answer)

Correct answer: Beam hardening from bone and soft tissue interfaces

Dense cortical bone at the shoulder causes beam hardening, producing characteristic streak artifacts that radiate into adjacent soft tissues.

Question 80: A 'blooming artifact' in CT most commonly results from:

High-density metallic objects causing overestimation of structure size (Correct answer)
Incorrect HU calibration of the scanner
Patient motion during acquisition
Undersampling of high-frequency data

Correct answer: High-density metallic objects causing overestimation of structure size

Blooming occurs when high-attenuation objects like metals or calcifications appear larger than their true size due to beam hardening and partial volume effects.

Question 81: A technologist holds both ARRT Radiography (R) and MRI (MR) credentials. To add CT certification, which credential serves as the qualifying primary pathway?

Only Radiography (R) qualifies
Both credentials must be listed; neither alone qualifies
Only MRI (MR) qualifies
Either R or MR can serve as the qualifying primary credential (Correct answer)

Correct answer: Either R or MR can serve as the qualifying primary credential

ARRT allows multiple qualifying primary pathways for CT, so either an active R or MR credential can serve as the qualifying base.

Question 82: What does CT stand for in medical imaging?

Cardiac Testing
Clinical Therapy
Central Treatment
Computed Tomography (Correct answer)

Correct answer: Computed Tomography

CT (Computed Tomography) uses X-ray technology and computer processing to create detailed cross-sectional images of the body.

Question 83: Which reconstruction kernel (filter) should be chosen to minimize noise when imaging soft tissue structures in the abdomen?

Smooth or standard soft tissue kernel (Correct answer)
Bone or edge-enhancing kernel
Ultra-high resolution kernel
Lung kernel

Correct answer: Smooth or standard soft tissue kernel

Soft tissue kernels apply low-pass filtering that smooths the image and reduces noise, which is appropriate for abdominal soft tissue evaluation.

Question 84: The ARRT Standards of Ethics is incorporated into the CT certification process primarily to:

Assess candidates' academic GPA
Ensure candidates demonstrate professional integrity and moral character (Correct answer)
Verify candidates' financial standing
Confirm candidates' insurance coverage

Correct answer: Ensure candidates demonstrate professional integrity and moral character

The Standards of Ethics screening ensures that only individuals with demonstrated professional integrity are certified.

Question 85: What is a Hounsfield unit?

A unit of radiation dose
A measure of scan speed
A quantitative measurement of tissue density on CT images (Correct answer)
A unit of image resolution

Correct answer: A quantitative measurement of tissue density on CT images

Hounsfield units (HU) measure tissue density on CT, with water at 0 HU, air at -1000 HU, and dense bone at +1000 HU or higher.

Question 86: An ARRT-certified CT technologist moves to a state that also requires state licensure for CT practice. Which statement is true?

ARRT certification replaces all state licensing requirements
State licensure CE requirements always mirror ARRT requirements exactly
ARRT automatically notifies the state upon renewal
State licensure and ARRT certification are separate and both may be required (Correct answer)

Correct answer: State licensure and ARRT certification are separate and both may be required

ARRT certification and state licensure are independent processes; meeting ARRT standards does not automatically satisfy state licensing requirements.

Question 87: When evaluating a CT image for streak artifacts emanating from a hip prosthesis, the BEST corrective technique is:

Increasing the kVp to 140
Decreasing the mAs by 50%
Metal artifact reduction (MAR) reconstruction algorithm (Correct answer)
Widening the reconstruction FOV

Correct answer: Metal artifact reduction (MAR) reconstruction algorithm

Metal artifact reduction algorithms use iterative or sinogram-based techniques to model and subtract metal-induced streaks from the image.

Question 88: In CT quality control, 'low-contrast detectability' refers to the system's ability to:

Measure exact CT numbers for each tissue type
Determine the maximum scan field of view
Distinguish objects with small differences in attenuation from background (Correct answer)
Resolve fine structural detail in bone

Correct answer: Distinguish objects with small differences in attenuation from background

Low-contrast detectability measures the scanner's ability to visualize objects with subtle attenuation differences, which is critical for soft-tissue diagnosis.

Question 89: Which CT quality control phantom is most commonly used to evaluate CT number accuracy, noise, uniformity, and spatial resolution?

Alderson Rando phantom
AAPM CT performance phantom (Correct answer)
MOSFET dosimetry phantom
Leeds TOR phantom

Correct answer: AAPM CT performance phantom

The AAPM CT performance phantom contains inserts for testing multiple image quality parameters including HU accuracy, noise, and spatial resolution.

Question 90: A technologist holds ARRT primary certification in Radiography and a post-primary in CT. How many total CE credits are required per cycle?

48 total — 24 for each credential separately
24 total, shared across both credentials (Correct answer)
24 total, with at least 6 specific to CT
36 total — 24 for primary plus 12 for post-primary

Correct answer: 24 total, shared across both credentials

ARRT allows the same 24 Category A CE credits to satisfy renewal requirements for both the primary and post-primary certifications simultaneously.

Question 91: What is the primary purpose of the CT dose index (CTDI)?

To calculate the effective dose to the technologist
To characterize radiation output of a CT scanner independent of patient size (Correct answer)
To determine scatter radiation levels in the control room
To measure patient absorbed dose in a single organ

Correct answer: To characterize radiation output of a CT scanner independent of patient size

CTDI characterizes the radiation output of a CT scanner and allows standardized comparison between scanners and protocols.

Question 92: The Hounsfield unit (HU) value of pure water is:

-1000
+1000
+100
0 (Correct answer)

Correct answer: 0

By definition, pure water is assigned an HU value of 0 on the Hounsfield scale used in CT imaging.

Question 93: The 'noise power spectrum' (NPS) in CT characterizes noise by:

Measuring total noise as a single RMS value
Comparing noise before and after contrast injection
Describing how noise energy is distributed across spatial frequencies (Correct answer)
Counting the number of noisy pixels per slice

Correct answer: Describing how noise energy is distributed across spatial frequencies

The NPS (or Wiener spectrum) describes the frequency distribution of noise variance, distinguishing coarse (low-frequency) from fine (high-frequency) noise textures.

Question 94: Which of the following scan coverage ranges is standard for a CT of the abdomen and pelvis?

Diaphragm to pubic symphysis (Correct answer)
Diaphragm to iliac crests only
Umbilicus to pubic symphysis
Lung apices to pubic symphysis

Correct answer: Diaphragm to pubic symphysis

A standard abdomen and pelvis CT extends from the diaphragm superiorly to the pubic symphysis inferiorly to cover all abdominal and pelvic organs.

Question 95: What is the primary advantage of CT over conventional X-ray?

CT uses no radiation
CT is cheaper
CT provides cross-sectional images with superior soft tissue contrast (Correct answer)
CT takes less time

Correct answer: CT provides cross-sectional images with superior soft tissue contrast

CT provides detailed cross-sectional images with much better soft tissue contrast resolution than conventional X-rays, allowing visualization of subtle differences between tissues.

Question 96: Respiratory motion artifacts on chest CT can best be minimized by:

Increasing kVp
Widening the display window
Using breath-hold technique during acquisition (Correct answer)
Increasing slice thickness

Correct answer: Using breath-hold technique during acquisition

Instructing the patient to suspend respiration during CT acquisition eliminates breathing motion, preventing blurring and step artifacts in the chest.

Question 97: A contrast CT of the abdomen shows a 'whirl sign' in the mesentery. What condition does this indicate?

Closed-loop small bowel obstruction with volvulus (Correct answer)
Appendicitis
Mesenteric adenitis
Bowel perforation

Correct answer: Closed-loop small bowel obstruction with volvulus

The whirl sign on CT represents twisting of mesenteric vessels and bowel loops, indicating volvulus typically causing closed-loop obstruction.

Question 98: In CT quality control documentation, what is the purpose of establishing 'action limits' for QC measurements?

To set thresholds that, when exceeded, require investigation and corrective action before clinical use (Correct answer)
To determine the minimum number of QC tests per week
To define the maximum patient dose per study
To establish the contrast media injection rate limits

Correct answer: To set thresholds that, when exceeded, require investigation and corrective action before clinical use

Action limits define tolerance thresholds for QC parameters; if a measurement falls outside these limits, the scanner must be taken out of service for investigation and repair.

Question 99: A CT technologist retires and allows their ARRT registration to expire for 8 years, then wishes to return to practice. What is required?

Retaking the ARRT CT certification examination (Correct answer)
A letter of recommendation from a radiologist
Completion of 24 CE credits and a reinstatement fee
Submission of a reinstatement fee only

Correct answer: Retaking the ARRT CT certification examination

After an extended lapse beyond ARRT's reinstatement window, technologists are typically required to retake the certification examination to demonstrate current competency.

Question 100: Which type of CT detector material is most commonly used in modern multi-detector CT (MDCT) systems due to its high conversion efficiency and fast decay time?

Gadolinium oxysulfide (GOS) solid-state scintillators (Correct answer)
Xenon gas ionization chambers
Sodium iodide (NaI) crystal detectors
Bismuth germanate (BGO) crystals

Correct answer: Gadolinium oxysulfide (GOS) solid-state scintillators

Modern MDCT scanners predominantly use solid-state scintillator detectors such as gadolinium oxysulfide because of their high X-ray absorption efficiency and rapid afterglow decay.

Question 101: The spatial resolution of a CT image is primarily limited by which factor?

Type of reconstruction filter used alone
Room temperature
Patient age
Focal spot size and detector aperture (Correct answer)

Correct answer: Focal spot size and detector aperture

Focal spot size and detector cell aperture are the primary hardware factors limiting spatial resolution in CT.

Question 102: What is the application window for the ARRT CT post-primary examination after a candidate is deemed eligible?

Six months from approval to test
30 days from approval to test
Two years from approval to test
One year from approval to test (Correct answer)

Correct answer: One year from approval to test

Once approved, ARRT candidates have one year to schedule and sit for the post-primary CT examination.

Question 103: A CT technologist is audited by ARRT and cannot produce records for completed CE activities. What is the most likely consequence?

ARRT will contact the CE sponsors on their behalf
A formal written warning is issued
They are required to repeat the certification exam
Their CE credits may be disallowed and registration revoked (Correct answer)

Correct answer: Their CE credits may be disallowed and registration revoked

During an audit, failure to document CE activities can result in disallowance of credits and potential revocation of registration.

Question 104: The dose length product (DLP) is calculated by multiplying CTDI_vol by which parameter?

Scan length (cm) (Correct answer)
Rotation time
Number of detector rows
Pitch factor

Correct answer: Scan length (cm)

DLP = CTDI_vol × scan length (cm), providing a single value that reflects the total radiation energy deposited during the scan.

Question 105: Which of the following would trigger an automatic review by the ARRT Ethics Review Committee?

A program director retiring
A technologist changing their employer
A credential holder being convicted of a felony (Correct answer)
A technologist failing to submit CE on time

Correct answer: A credential holder being convicted of a felony

A felony conviction is a serious ethics matter that ARRT's Ethics Review Committee must evaluate to determine whether the credential can be maintained.

Question 106: What is the difference between arteries and veins?

Veins are thicker than arteries
They carry the same blood in the same direction
Arteries are only in the lungs
Arteries carry blood away from the heart; veins carry blood toward the heart (Correct answer)

Correct answer: Arteries carry blood away from the heart; veins carry blood toward the heart

Arteries carry blood away from the heart (usually oxygenated) while veins carry blood toward the heart (usually deoxygenated). Arteries have thicker walls to handle higher pressure.

Question 107: Which of the following BEST describes noise power spectrum (NPS) in CT?

A measure of how noise is distributed across spatial frequencies in an image (Correct answer)
A test of detector linearity across HU ranges
The ratio of signal to total detector noise
The standard deviation of HU values in a uniform phantom

Correct answer: A measure of how noise is distributed across spatial frequencies in an image

NPS characterizes the frequency content of image noise, showing whether noise is more granular (high-frequency) or blotchy (low-frequency) depending on reconstruction parameters.

Question 108: What is the role of the bowtie (beam-shaping) filter in CT equipment operation?

To equalize X-ray flux across the fan beam, reducing dose at the periphery and minimizing detector saturation (Correct answer)
To collimate the beam to the prescribed slice thickness
To harden the beam and remove low-energy photons uniformly across the beam
To increase photon energy for improved tissue penetration

Correct answer: To equalize X-ray flux across the fan beam, reducing dose at the periphery and minimizing detector saturation

The bowtie filter is thicker at the edges and thinner at the center, compensating for the cylindrical shape of patients to equalize detector flux and reduce peripheral skin dose.

Question 109: For a pancreatic protocol CT, which phase is most critical for detecting hypervascular pancreatic neuroendocrine tumors?

Unenhanced phase
Portal venous phase at 70 seconds
Late arterial (pancreatic parenchymal) phase at 40–50 seconds (Correct answer)
Delayed phase at 5 minutes

Correct answer: Late arterial (pancreatic parenchymal) phase at 40–50 seconds

Pancreatic neuroendocrine tumors are hypervascular and enhance most conspicuously during the pancreatic parenchymal phase (approximately 40–50 seconds), when the pancreas peaks in enhancement.

Question 110: Which of the following primary credentials does NOT qualify a technologist to sit for the ARRT CT post-primary examination?

Radiation Therapy (T)
Chiropractic (DACBR) (Correct answer)
Nuclear Medicine Technology (N)
Radiography (R)

Correct answer: Chiropractic (DACBR)

Chiropractic radiology is not an ARRT-recognized qualifying primary pathway for CT post-primary eligibility.

Question 111: The Hounsfield unit (HU) value of pure water is defined as:

+1000 HU
+500 HU
-1000 HU
0 HU (Correct answer)

Correct answer: 0 HU

The CT number scale defines water as 0 HU and air as −1000 HU, with other tissues placed relative to these references.

Question 112: To meet ARRT’s ethics requirements, which of the following is necessary?

Agree to follow the ARRT Standards of Ethics and report any potential violations (Correct answer)
Take a separate ethics exam during the certification process
Submit a personal statement of professional ethics
Pass a background check and provide character references

Correct answer: Agree to follow the ARRT Standards of Ethics and report any potential violations

The ARRT places a strong emphasis on ethical conduct within the radiologic technology profession. To meet their ethics requirements, candidates must formally agree to adhere to the ARRT Standards of Ethics, which outline professional responsibilities and conduct. This commitment includes reporting any potential violations, upholding the integrity of the profession.

Question 113: A technologist is scanning a patient with metal hip implants. To reduce dose while managing metal artifact, which approach is MOST appropriate?

Skip the hip region entirely regardless of clinical indication
Double the mAs in the hip region to overpower artifacts
Use metal artifact reduction (MAR) software at standard dose rather than routinely increasing mAs (Correct answer)
Switch to a lower kVp to increase contrast resolution

Correct answer: Use metal artifact reduction (MAR) software at standard dose rather than routinely increasing mAs

Metal artifact reduction software effectively manages implant artifacts at standard dose; routinely increasing mAs adds unnecessary patient dose without eliminating artifacts.

Question 114: Which window setting is most appropriate for evaluating pulmonary nodules in the lung parenchyma?

Window width ~1500 HU, window level ~-600 HU (Correct answer)
Window width ~400 HU, window level ~40 HU
Window width ~3000 HU, window level ~300 HU
Window width ~200 HU, window level ~80 HU

Correct answer: Window width ~1500 HU, window level ~-600 HU

Lung windows use a wide width (~1500 HU) and negative level (~-600 HU) to display the full range of lung attenuation from air to soft tissue.

Question 115: What is the ALARA principle in radiation safety?

As Low As Reasonably Achievable — minimize radiation exposure (Correct answer)
Automated Limiting Adjustment for Radiation Applications
All Labs And Rooms Assessed
Always Lock And Restrict Access

Correct answer: As Low As Reasonably Achievable — minimize radiation exposure

ALARA means keeping radiation doses as low as reasonably achievable while still obtaining diagnostic-quality images, balancing benefit against risk.

Question 116: A candidate who completed a structured education program in radiologic technology but has not yet passed their primary certification exam may:

Apply for CT immediately after graduation
Not apply for CT until the primary credential is active and unrestricted (Correct answer)
Apply for CT under a provisional license
Apply for CT if supervised by a radiologist

Correct answer: Not apply for CT until the primary credential is active and unrestricted

Candidates must hold an active, unrestricted primary credential before applying for the CT post-primary examination.

Question 117: ARRT certification in CT is best described as which type of credential?

Entry-level primary certification
Post-primary specialty certification (Correct answer)
Academic degree credential
State-issued license

Correct answer: Post-primary specialty certification

CT certification is a post-primary specialty credential, meaning it is layered on top of a primary ARRT certification in a related discipline.

Question 118: A CT scan for appendicitis in a young female patient of childbearing age should be preceded by:

Double dose of IV contrast
Administration of glucagon
Evaluation for pregnancy and consideration of alternative imaging (Correct answer)
Lung window reconstruction

Correct answer: Evaluation for pregnancy and consideration of alternative imaging

Radiation dose to a fetus is a critical concern; pregnancy should be assessed and ultrasound or MRI considered as alternatives before CT in reproductive-age females.

Question 119: When performing a CT pulmonary angiography (CTPA), which scan direction is preferred?

Caudal to cranial (Correct answer)
Bidirectional
Cranial to caudal
Either direction equally

Correct answer: Caudal to cranial

Caudal-to-cranial scanning in CTPA ensures the densest contrast bolus reaches the pulmonary arteries during image acquisition.

Question 120: A patient with a serum creatinine of 1.8 mg/dL is scheduled for a contrast-enhanced CT. Which action is most appropriate?

Proceed normally with standard iodinated contrast dose
Switch to gadolinium-based contrast agent
Cancel the exam entirely without further evaluation
Notify the radiologist and consider pre-hydration protocols (Correct answer)

Correct answer: Notify the radiologist and consider pre-hydration protocols

Elevated creatinine indicates impaired renal function, requiring radiologist notification and consideration of pre-hydration or dose reduction to minimize contrast-induced nephropathy risk.

Question 121: What is the primary radiation hazard associated with CT compared to conventional radiography?

Higher peak kilovoltage
Use of radioactive isotopes as contrast agents
Greater secondary radiation reaching personnel in adjacent rooms
Significantly greater patient dose due to multiple rotational acquisitions and extended scan volumes (Correct answer)

Correct answer: Significantly greater patient dose due to multiple rotational acquisitions and extended scan volumes

CT delivers substantially higher patient doses than conventional radiography because it involves multiple rotational X-ray acquisitions covering large anatomical volumes.

Question 122: Increasing the x-ray tube voltage (kVp) in CT primarily results in:

Higher image noise and lower contrast
Unchanged image quality but increased scan time
Lower mean photon energy and higher subject contrast
Higher mean photon energy and reduced photoelectric interactions (Correct answer)

Correct answer: Higher mean photon energy and reduced photoelectric interactions

Higher kVp produces a higher mean photon energy beam with greater penetrating power; Compton scatter dominates over photoelectric effect, reducing subject contrast.

Question 123: On CT of the head, lenticular (biconvex) hyperdensity is identified adjacent to the temporal bone. What is the most likely cause?

Hypertensive hemorrhage
Middle meningeal artery rupture causing epidural hematoma (Correct answer)
Berry aneurysm rupture
Bridging vein rupture causing subdural hematoma

Correct answer: Middle meningeal artery rupture causing epidural hematoma

Epidural hematomas result from middle meningeal artery injury and form a biconvex hyperdense collection limited by dural attachments at sutures.

Question 124: Iterative reconstruction (IR) techniques in CT offer which primary advantage over filtered back projection?

Faster reconstruction speed
Reduced image noise at the same or lower radiation dose (Correct answer)
Elimination of all artifacts
Higher spatial resolution

Correct answer: Reduced image noise at the same or lower radiation dose

IR algorithms use repeated mathematical modeling of the imaging process to suppress noise, allowing diagnostic image quality to be maintained at reduced mAs and dose.

Question 125: For a trauma CT protocol of the chest, which contrast phase is typically acquired?

Non-contrast only
Arterial phase only
Portal venous phase (Correct answer)
Delayed phase only

Correct answer: Portal venous phase

The portal venous phase (~60–70 seconds post-injection) provides optimal parenchymal enhancement to detect solid organ injuries in chest trauma.

Question 126: In CT, contrast-to-noise ratio (CNR) is BEST described as:

The difference in HU between two structures divided by image noise (Correct answer)
The number of line pairs per centimeter resolved
The ability to detect objects of varying sizes
The ratio of signal to detector dark current

Correct answer: The difference in HU between two structures divided by image noise

CNR = (HU_structure − HU_background) ÷ noise standard deviation, quantifying how well a structure stands out against background noise.

Question 127: Multiplanar reformation (MPR) in CT refers to:

Applying color to CT images based on Hounsfield units
Generating 3D surface models from volumetric data
Reconstructing axial images into coronal, sagittal, or oblique planes (Correct answer)
Subtracting pre-contrast from post-contrast images

Correct answer: Reconstructing axial images into coronal, sagittal, or oblique planes

MPR uses the volumetric CT dataset to create reformatted images in any anatomical plane without additional radiation exposure to the patient.

Question 128: Which of the following best describes an out-of-field artifact in CT?

Streaking caused by anatomy extending beyond the scan FOV (Correct answer)
Noise from low mAs
Blurring from respiratory motion
Ring caused by detector failure

Correct answer: Streaking caused by anatomy extending beyond the scan FOV

Out-of-field artifacts occur when part of the patient's anatomy lies outside the calibrated scan FOV, causing truncation of projection data and bright peripheral streaks.

Question 129: When creating coronal MPR images from a helical chest CT, image quality is best when the original acquisition used:

Thin slices (≤1 mm) reconstructed at overlapping intervals (0.5–0.7 mm) (Correct answer)
Thick slices (5–10 mm) reconstructed at 5 mm intervals
High pitch with standard soft tissue kernel only
Large FOV and minimal overlap

Correct answer: Thin slices (≤1 mm) reconstructed at overlapping intervals (0.5–0.7 mm)

Thin, overlapping reconstructions produce near-isotropic voxels that allow high-quality coronal and sagittal reformations without visible stair-step artifacts.

Question 130: A CT technologist notices the dose reference level (DRL) for a routine chest CT is being routinely exceeded. The BEST first step is to:

Review and optimize the scan protocol to determine if dose can be reduced without compromising diagnostic quality (Correct answer)
Continue scanning since DRLs are not legally binding limits
Report the finding only to the radiologist and take no further action
Immediately halve the mAs for all chest CT exams

Correct answer: Review and optimize the scan protocol to determine if dose can be reduced without compromising diagnostic quality

DRLs serve as benchmarks; exceeding them triggers a protocol review to identify optimization opportunities while preserving diagnostic image quality.

Question 131: A patient weighing 300 lbs is scanned using a standard adult protocol. How should the technologist respond?

Use pediatric technique factors
Reduce mAs by 50% regardless of image quality
Increase kVp to 140 and decrease mAs proportionally
Apply size-specific dose estimates (SSDE) and adjust technique for body habitus (Correct answer)

Correct answer: Apply size-specific dose estimates (SSDE) and adjust technique for body habitus

SSDE accounts for patient size and provides a more accurate dose estimate; technique should be adjusted to match body habitus while maintaining diagnostic quality.

Question 132: A ring or band artifact centered on the image is most likely caused by a malfunction of which CT component?

Collimator
A single detector element (Correct answer)
X-ray tube
Gantry motor

Correct answer: A single detector element

Ring artifacts result from a miscalibrated or malfunctioning detector element producing a circular artifact at a fixed radius from the isocenter.

Question 133: When a CT abdomen protocol specifies 'nephrographic phase,' scanning typically occurs at what delay after IV contrast injection?

5–10 minutes
80–120 seconds (Correct answer)
30–45 seconds
15–25 seconds

Correct answer: 80–120 seconds

The nephrographic phase occurs at approximately 80–120 seconds post-injection when both cortex and medulla enhance uniformly, optimizing renal parenchymal visualization.

Question 134: Increasing the reconstruction field of view (FOV) while keeping matrix size constant will:

Increase pixel size and decrease spatial resolution (Correct answer)
Increase noise while improving contrast
Decrease pixel size and increase spatial resolution
Have no effect on spatial resolution

Correct answer: Increase pixel size and decrease spatial resolution

Larger FOV with the same matrix means each pixel covers more area, increasing pixel size and reducing spatial resolution.

Question 135: On axial CT of the abdomen, the superior mesenteric artery (SMA) is typically located:

Within the hepatoduodenal ligament
Posterior to the splenic vein
Directly anterior to the abdominal aorta, surrounded by fat (Correct answer)
Lateral to the inferior vena cava

Correct answer: Directly anterior to the abdominal aorta, surrounded by fat

The SMA arises from the anterior aorta and is typically seen as a vessel surrounded by a halo of mesenteric fat on axial CT.

Question 136: In CT, the filtered back projection (FBP) reconstruction algorithm applies a mathematical filter primarily to:

Correct for star artifacts inherent in simple back projection (Correct answer)
Align misregistered projection data
Segment soft tissue from bone
Remove quantum noise before reconstruction

Correct answer: Correct for star artifacts inherent in simple back projection

FBP applies a ramp or other convolution filter to projection data before back-projecting to eliminate the blurring ('star artifact') produced by simple back projection.

Question 137: Which CT image quality parameter is measured using a modulation transfer function (MTF)?

Contrast resolution
Temporal resolution
Spatial resolution (Correct answer)
Noise power spectrum

Correct answer: Spatial resolution

The MTF quantifies spatial resolution by describing how faithfully the CT system reproduces objects of varying spatial frequencies.

Question 138: What physiologic mechanism underlies contrast-induced nephropathy (CIN)?

Systemic vasodilation leading to prerenal azotemia
Obstructive uropathy from contrast precipitation in the collecting ducts
Immune-mediated glomerulonephritis triggered by iodine
Renal medullary ischemia and direct tubular cell toxicity from contrast (Correct answer)

Correct answer: Renal medullary ischemia and direct tubular cell toxicity from contrast

CIN results from renal medullary vasoconstriction causing ischemia combined with direct cytotoxic effects of contrast on tubular epithelial cells.

Question 139: Which vital sign finding in an adult patient should be reported to the supervising clinician before proceeding with a routine radiographic exam?

Blood pressure of 118/76 mmHg
Temperature of 98.6°F (37°C)
Pulse of 72 beats per minute
Respiratory rate of 10 breaths per minute (Correct answer)

Correct answer: Respiratory rate of 10 breaths per minute

A respiratory rate of 10 breaths per minute is below the normal range (12-20) and indicates bradypnea, which warrants clinical notification.

Question 140: A CT chest in a patient with AIDS shows bilateral ground-glass opacities in a 'bat-wing' distribution. The most likely diagnosis is:

Pneumocystis jirovecii pneumonia (Correct answer)
Mycobacterium avium complex
Cytomegalovirus pneumonitis
Kaposi sarcoma

Correct answer: Pneumocystis jirovecii pneumonia

PCP (Pneumocystis jirovecii pneumonia) classically presents with bilateral perihilar ground-glass opacities in immunocompromised patients.

Question 141: Which reconstruction field of view (FOV) is most appropriate when performing targeted high-resolution CT of the temporal bone?

10–15 cm (small targeted FOV) (Correct answer)
40 cm (large FOV)
25 cm (medium FOV)
50 cm (full body FOV)

Correct answer: 10–15 cm (small targeted FOV)

A 10–15 cm reconstruction FOV over the temporal bone maximizes pixel density within the small region of interest, yielding the highest possible spatial resolution.

Question 142: CT perfusion imaging requires specialized post-processing to generate which type of parametric maps?

Standardized uptake value (SUV) maps
Cerebral blood flow, cerebral blood volume, and mean transit time maps (Correct answer)
Bone mineral density scores
Hounsfield unit histograms

Correct answer: Cerebral blood flow, cerebral blood volume, and mean transit time maps

CT perfusion post-processing applies deconvolution or maximum slope models to time-attenuation curves to produce quantitative maps of CBF, CBV, and MTT.

Question 143: A patient states, 'I am Jehovah's Witness and refuse any blood transfusion.' The radiologic technologist should:

Contact the patient's family to override the decision
Disregard the statement as the patient may not understand their condition
Proceed with the procedure and allow physicians to decide later
Document the statement and notify the supervising clinician immediately (Correct answer)

Correct answer: Document the statement and notify the supervising clinician immediately

A competent adult patient has the right to refuse treatment; the technologist must document this and notify the care team to ensure informed refusal is properly handled.

Question 144: The window level (WL) in CT display refers to:

The minimum threshold for bone segmentation
The center Hounsfield unit value of the displayed grayscale range (Correct answer)
The total range of Hounsfield units shown
The reconstruction matrix size

Correct answer: The center Hounsfield unit value of the displayed grayscale range

Window level sets the midpoint of the HU range being displayed, determining which tissue densities appear as medium gray on the monitor.

Question 145: What is the maximum number of times a candidate may attempt the ARRT CT examination?

Unlimited attempts within the eligibility window
6 times total (Correct answer)
No limit on attempts, but a new application is required after 3 failures
3 times total

Correct answer: 6 times total

ARRT allows a maximum of 6 examination attempts for any given credential.

Question 146: What is one key reason that ACR-accredited imaging facilities value technologists with ARRT CT certification?

Accreditation requires a minimum ratio of 10 certified techs per scanner
ACR accreditation prohibits hiring uncertified technologists
ARRT CT certification is issued by the ACR
Certified technologists help demonstrate staff qualifications required during ACR accreditation reviews (Correct answer)

Correct answer: Certified technologists help demonstrate staff qualifications required during ACR accreditation reviews

ACR accreditation reviewers assess staff qualifications, and ARRT CT certification is recognized evidence of competency that supports accreditation approval.

Question 147: A CT technologist with ARRT CT certification wants to teach at a community college radiologic technology program. How does the certification help?

It only qualifies the technologist to teach radiography, not CT specifically
It is a disqualifying credential for educational roles
It automatically grants a teaching license in all states
It demonstrates content expertise that many programs require or prefer for adjunct CT instructors (Correct answer)

Correct answer: It demonstrates content expertise that many programs require or prefer for adjunct CT instructors

Community college and vocational radiologic technology programs often require or prefer instructors to hold advanced ARRT credentials in the specialty they are teaching.

Question 148: Which pitch factor would result in the longest scan time for a given scan range?

2.0
1.5
1.0
0.5 (Correct answer)

Correct answer: 0.5

A lower pitch means the table moves more slowly relative to rotation speed, resulting in more overlap and a longer scan time.

Question 149: For a pediatric CT head scan, compared to an adult protocol, the technologist should generally:

Increase kVp to 140 kV to penetrate the skull
Reduce mAs significantly because children are more radiosensitive and smaller (Correct answer)
Use the same mAs to ensure adequate image quality
Extend scan length to cover the entire neuraxis

Correct answer: Reduce mAs significantly because children are more radiosensitive and smaller

Children have greater radiosensitivity and smaller body dimensions, so pediatric CT protocols use substantially lower mAs than adult protocols.

Question 150: During a CT pulmonary angiography, the technologist notices extravasation of contrast at the injection site. What is the first action?

Increase the injection pressure to maintain flow
Switch to a new injection site and restart the injection
Continue the injection at a slower rate
Stop the injection immediately and notify the radiologist (Correct answer)

Correct answer: Stop the injection immediately and notify the radiologist

Extravasation can cause tissue injury; the injection must be stopped immediately and the radiologist informed for proper management.

Question 151: A Radiation Therapy (T) credential holder who wishes to obtain CT certification must complete which category of clinical competencies?

Radiography general competencies only
CT-specific competencies as outlined in the ARRT CT content specifications (Correct answer)
MRI competencies as a prerequisite
No clinical competencies — written exam only

Correct answer: CT-specific competencies as outlined in the ARRT CT content specifications

All CT candidates, regardless of their primary pathway, must satisfy CT-specific clinical competency requirements.

Question 152: A horizontal band of decreased attenuation passing through the posterior fossa on a head CT is a classic example of which artifact?

Motion artifact from cardiac pulsation
Ring artifact
Beam hardening between the petrous bones (Correct answer)
Partial volume artifact

Correct answer: Beam hardening between the petrous bones

The dense petrous temporal bones cause preferential absorption of lower-energy photons, producing a dark band across the posterior fossa known as a beam hardening artifact.

Question 153: A CT abdomen in a trauma patient shows high-density fluid in the hepatorenal space (Morison's pouch). What does this indicate?

Hemoperitoneum (Correct answer)
Biliary leak
Lymphocele
Physiologic peritoneal fluid

Correct answer: Hemoperitoneum

High-attenuation free fluid (>30 HU) in Morison's pouch following trauma indicates hemoperitoneum from solid organ or vascular injury.

Question 154: What is the primary purpose of the ARRT's preapplication review process?

To expedite exam scheduling for experienced technologists
To waive the examination fee for qualified applicants
To substitute for clinical competency documentation
To allow individuals with potential ethics issues to determine eligibility before investing in education (Correct answer)

Correct answer: To allow individuals with potential ethics issues to determine eligibility before investing in education

The preapplication review lets individuals with past ethical issues get a preliminary ruling on eligibility before completing an educational program.

Question 155: The pitch value in helical CT is defined as:

Slice thickness divided by detector row width
Gantry rotation speed divided by table speed
Table travel per rotation divided by total beam collimation width (Correct answer)
kVp divided by mA

Correct answer: Table travel per rotation divided by total beam collimation width

Pitch = table distance traveled per 360° rotation ÷ total collimated beam width, and values >1 indicate gaps in data coverage.

Question 156: What is the NATO phonetic alphabet letter for 'B'?

Boy
Bravo (Correct answer)
Beta
Baker

Correct answer: Bravo

In the NATO phonetic alphabet, 'B' is represented by 'Bravo.' This ensures clear radio communication.

Question 157: On a CT image at the level of C6, which structure occupies the anterior midline of the neck?

Common carotid artery
Esophagus
Trachea
Thyroid gland (Correct answer)

Correct answer: Thyroid gland

The thyroid gland wraps anteriorly around the trachea at the C5-C6 level, occupying the anterior midline.

Question 158: On axial CT at the level of L4-L5, which structure is found anterior to the vertebral body?

Celiac axis
Inferior mesenteric artery origin
Superior mesenteric artery origin
Abdominal aortic bifurcation (Correct answer)

Correct answer: Abdominal aortic bifurcation

The abdominal aorta bifurcates into the common iliac arteries at approximately the L4 vertebral level.

Question 159: Which of the following best explains why ARRT periodically revises its CT examination content specifications?

To match content used by competing certification bodies
To increase examination difficulty and reduce pass rates
To satisfy JRCERT annual audit requirements
To align the examination with evolving clinical practice identified through practice analysis (Correct answer)

Correct answer: To align the examination with evolving clinical practice identified through practice analysis

ARRT updates content specifications based on practice analysis data to ensure examinations reflect what entry-level technologists actually need to know in current clinical settings.

Question 160: Which scan phase best demonstrates hepatic metastases that are hypervascular?

Portal venous phase
Delayed phase
Hepatic arterial phase (Correct answer)
Non-contrast phase

Correct answer: Hepatic arterial phase

Hypervascular metastases enhance avidly during the hepatic arterial phase when liver parenchyma enhancement is low, maximizing lesion-to-liver contrast.

Question 161: Which career pathway is most directly opened by holding ARRT CT certification?

Lead CT technologist or CT supervisor (Correct answer)
Radiology billing and coding specialist
Radiation oncology physician assistant
Nuclear medicine physician

Correct answer: Lead CT technologist or CT supervisor

CT certification establishes the specialized credential often required for leadership roles such as lead CT tech or CT department supervisor.

Question 162: What is the largest organ in the human body?

Brain
Liver
Heart
Skin (Correct answer)

Correct answer: Skin

The skin is the largest organ, covering approximately 20 square feet in adults and weighing about 8 pounds. It serves as the primary barrier against the environment.

Question 163: CT of the abdomen in a cirrhotic patient shows multiple enhancing nodules in the liver. Which additional finding would most strongly suggest hepatocellular carcinoma over regenerative nodules?

Washout appearance on delayed phase imaging (Correct answer)
Nodule size less than 1 cm
Homogeneous enhancement in all phases
T2 hypointensity on MRI

Correct answer: Washout appearance on delayed phase imaging

Arterial enhancement followed by washout on portal venous or delayed phase is the LI-RADS CT hallmark distinguishing HCC from benign regenerative nodules.

Question 164: What does CT stand for in medical imaging?

Clinical Therapy
Computed Tomography (Correct answer)
Central Treatment
Cardiac Testing

Correct answer: Computed Tomography

CT (Computed Tomography) uses X-ray technology and computer processing to create detailed cross-sectional images of the body.

Question 165: On a sagittal CT reconstruction of the chest, the azygos vein is best identified by its arch over which structure?

The right main bronchus (Correct answer)
The superior vena cava
The left main bronchus
The right pulmonary artery

Correct answer: The right main bronchus

The azygos vein arches over the right main bronchus before draining into the posterior superior vena cava.

Question 166: When transferring a patient from a wheelchair to the radiographic table, the wheelchair should be positioned at what angle relative to the table?

45 degrees (Correct answer)
90 degrees
Parallel and touching the table
180 degrees

Correct answer: 45 degrees

Positioning the wheelchair at approximately 45 degrees to the table allows the shortest, most controlled pivot transfer for the patient.

Question 167: When comparing filtered back projection (FBP) to model-based iterative reconstruction (MBIR) at matched noise levels, MBIR typically demonstrates:

Lower spatial resolution but equivalent noise
Equivalent resolution but increased beam hardening artifacts
Higher spatial resolution with fewer artifacts at lower dose (Correct answer)
Longer reconstruction times with no image quality advantage

Correct answer: Higher spatial resolution with fewer artifacts at lower dose

MBIR models the entire imaging chain including optics and statistics, achieving better resolution and artifact suppression at lower dose than FBP.

Question 168: CT of the neck in a patient with a palpable mass shows a cystic lesion at the angle of the mandible deep to the sternocleidomastoid muscle. This is most consistent with:

Branchial cleft cyst (Correct answer)
Lymphatic malformation
Dermoid cyst
Thyroglossal duct cyst

Correct answer: Branchial cleft cyst

Branchial cleft cysts characteristically appear as unilocular cystic masses at the angle of the mandible adjacent to the sternocleidomastoid muscle.

Question 169: The 'noise' measured in a CT image is quantified as:

The standard deviation of CT numbers in a uniform region of interest (Correct answer)
The mean CT number in a region of interest
The difference between maximum and minimum CT numbers in the image
The number of image artifacts present

Correct answer: The standard deviation of CT numbers in a uniform region of interest

Image noise in CT is quantified as the standard deviation of HU values within a uniform phantom region; higher standard deviation indicates greater noise.

Question 170: Which of the following best describes the CT appearance of the caudate lobe of the liver?

A small segment located between the IVC and the fissure for the ligamentum venosum (Correct answer)
Located posterior to the inferior vena cava and anterior to the portal vein
The largest segment of the left hepatic lobe
Located between the gallbladder fossa and the fissure for the ligamentum teres

Correct answer: A small segment located between the IVC and the fissure for the ligamentum venosum

The caudate lobe (segment I) lies between the IVC posteriorly and the fissure for the ligamentum venosum anteriorly.

Question 171: Automatic tube current modulation (ATCM) in CT primarily aims to:

Maintain consistent image noise while minimizing patient dose (Correct answer)
Eliminate motion artifacts in cardiac imaging
Improve temporal resolution in dynamic studies
Maximize image spatial resolution for all body regions

Correct answer: Maintain consistent image noise while minimizing patient dose

ATCM adjusts mA based on patient attenuation in real time, delivering higher current through thicker/denser regions to maintain uniform noise and reducing dose elsewhere.

Question 172: CT window width (WW) setting controls which aspect of image display?

The overall brightness of the image
The center Hounsfield unit of the gray scale
The spatial resolution of the image
The range of Hounsfield units displayed as the full gray scale from black to white (Correct answer)

Correct answer: The range of Hounsfield units displayed as the full gray scale from black to white

Window width determines the range of CT numbers (HU) mapped to the grayscale; a narrow window increases contrast but limits the HU range displayed.

Question 173: What is the window level and window width on CT images?

Physical measurements of the CT scanner
Patient positioning parameters
Scan speed controls
Settings that control the brightness and contrast of displayed images (Correct answer)

Correct answer: Settings that control the brightness and contrast of displayed images

Window level sets the center brightness (what HU appears as middle gray) and window width controls contrast range (how many HUs span from black to white).

Question 174: Which document must a CT examination candidate submit to verify completion of required clinical experience?

A personal statement of clinical hours
An IRS tax form showing employment
Attestation signed by the supervising radiologist or program director (Correct answer)
A letter from the hospital CEO

Correct answer: Attestation signed by the supervising radiologist or program director

ARRT requires an attestation from a qualified supervisor verifying that the candidate met clinical competency requirements.

Question 175: The ARRT CT examination is delivered at:

ARRT headquarters only
Pearson VUE testing centers (Correct answer)
Accredited radiologic technology schools
Online via live proctoring from any location

Correct answer: Pearson VUE testing centers

ARRT partners with Pearson VUE to administer the CT post-primary examination at authorized testing centers.

Question 176: Which CT parameter most directly controls the amount of radiation dose delivered to the patient?

Reconstruction kernel
kVp
mAs (Correct answer)
Pitch

Correct answer: mAs

mAs (milliampere-seconds) directly determines the number of X-ray photons produced and is the primary controller of patient dose.

Question 177: What documentation does an ARRT candidate typically need to submit to verify clinical competency in CT?

Competency verification signed by a supervising radiologist or qualified technologist (Correct answer)
Employer payroll records
ACR accreditation certificate of the facility
A letter from the state radiology board

Correct answer: Competency verification signed by a supervising radiologist or qualified technologist

Clinical competency must be verified by a supervising qualified professional who can attest that the candidate performed required procedures.

Question 178: Quantum mottle in CT images is primarily caused by:

Excessive table speed
An insufficient number of detected photons (Correct answer)
Detector calibration errors
High kVp beam hardening

Correct answer: An insufficient number of detected photons

Quantum mottle (noise) occurs when too few photons reach the detector, causing statistical fluctuations that appear as grainy image texture.

Question 179: 3D volume rendering of CT data allows the display of internal structures through which technique?

Subtracting bone from the dataset
Selecting only the highest attenuation voxel per projection ray
Applying a smooth kernel to the raw data
Assigning opacity values to voxels based on their Hounsfield units (Correct answer)

Correct answer: Assigning opacity values to voxels based on their Hounsfield units

Volume rendering assigns transfer functions that map each HU value to a color and opacity, allowing semi-transparent visualization of multiple tissue types simultaneously.

Question 180: Which measurement best quantifies the amount of iodine delivered to a patient per unit time during a CT angiography injection?

Iodine concentration in mg/mL alone
Injection pressure in PSI
Total contrast volume in mL
Iodine delivery rate (IDR) expressed as grams of iodine per second (Correct answer)

Correct answer: Iodine delivery rate (IDR) expressed as grams of iodine per second

Iodine delivery rate (IDR = concentration [mgI/mL] × flow rate [mL/s]) determines the rate of iodine reaching the vascular system and predicts enhancement quality better than volume alone.

Question 181: CT of the knee shows a hyperdense line through the distal femoral epiphysis crossing the growth plate. This finding represents:

Stress fracture
Salter-Harris type II fracture (Correct answer)
Osteochondral defect
Physeal bar formation

Correct answer: Salter-Harris type II fracture

A Salter-Harris type II fracture extends through the physis and exits through the metaphysis, the most common physeal injury type.

Question 182: Which window setting is most appropriate for evaluating acute intracranial hemorrhage on a non-contrast head CT?

Bone window (WW 2000, WL 300)
Soft tissue window (WW 400, WL 50)
Lung window (WW 1500, WL -500)
Brain window (WW 80, WL 35) (Correct answer)

Correct answer: Brain window (WW 80, WL 35)

The brain window (narrow width ~80 HU, level ~35 HU) provides optimal contrast between hyperdense blood and surrounding brain tissue.

Question 183: A CT image shows ring artifacts. The MOST likely cause is:

Patient motion during scanning
Incorrect kVp selection
Too low an mAs setting
A malfunctioning or miscalibrated detector element (Correct answer)

Correct answer: A malfunctioning or miscalibrated detector element

Ring artifacts appear as circular bands centered on the isocenter and are caused by a single detector element producing consistently incorrect readings.

Question 184: What is the correct technique for removing contaminated gloves to prevent self-contamination?

Pull both gloves off by the fingertips simultaneously
Snap gloves off at the wrist and discard immediately
Wash gloves with soap and water before removal
Peel one glove inside-out from the wrist, then use bare fingers inside the second glove's wrist to remove it (Correct answer)

Correct answer: Peel one glove inside-out from the wrist, then use bare fingers inside the second glove's wrist to remove it

The proper technique keeps contaminated outer surfaces folded inside during removal so bare skin never contacts the contaminated exterior.

Question 185: A patient asks the radiologic technologist about the radiation dose they will receive from a CT scan. The best response is to:

Dismiss the concern since modern CT scanners are considered completely safe
Provide a general explanation of the dose and the benefit-risk balance while referring detailed questions to the radiologist (Correct answer)
Tell the patient the dose information is confidential
Explain that CT doses are too complex to explain to patients

Correct answer: Provide a general explanation of the dose and the benefit-risk balance while referring detailed questions to the radiologist

Patients have the right to understand their radiation exposure; the technologist should provide a clear, honest explanation and involve the radiologist for detailed clinical questions.

Question 186: A patient with a cardiac pacemaker presents for chest CT. Which artifact should the technologist anticipate?

Cupping artifact
Ring artifact
Metallic streak artifact from the pacemaker leads and generator (Correct answer)
Windmill artifact

Correct answer: Metallic streak artifact from the pacemaker leads and generator

Pacemaker generators and leads are highly attenuating metallic objects that produce characteristic beam hardening streak artifacts on chest CT.

Question 187: The primary interaction of diagnostic x-ray photons with soft tissue in CT is:

Compton scattering (Correct answer)
Pair production
Photoelectric effect
Coherent (Rayleigh) scattering

Correct answer: Compton scattering

At the diagnostic energy range used in CT (typically 80–140 kVp), Compton scattering is the dominant interaction in soft tissue.

Question 188: A CT technologist is concerned about cumulative occupational dose. Which dosimeter provides the most accurate record of whole-body exposure?

Electronic personal dosimeter worn at waist
Pocket ionization chamber
Finger ring TLD
Optically stimulated luminescence (OSL) badge worn at collar level (Correct answer)

Correct answer: Optically stimulated luminescence (OSL) badge worn at collar level

An OSL badge worn at the collar (outside any lead apron) is the standard for whole-body occupational dose monitoring and provides accurate cumulative records.

Question 189: Stochastic effects of radiation are characterized by which of the following?

Occurring only in radiosensitive tissues such as bone marrow
A threshold dose below which the effect cannot occur
Severity increasing proportionally with dose above the threshold
No dose threshold; probability of occurrence increases with dose (Correct answer)

Correct answer: No dose threshold; probability of occurrence increases with dose

Stochastic effects (e.g., radiation-induced cancer) are assumed to have no threshold; their probability, not severity, increases with dose.

Question 190: When performing a CT colonography, the technologist selects a 0.625 mm detector row width versus 5 mm. This change PRIMARILY improves:

Contrast resolution for soft tissue differentiation
Patient dose efficiency
Longitudinal (z-axis) spatial resolution enabling multiplanar reformats (Correct answer)
Temporal resolution for cardiac gating

Correct answer: Longitudinal (z-axis) spatial resolution enabling multiplanar reformats

Thinner detector rows provide finer z-axis sampling, enabling isotropic voxels and high-quality multiplanar reformats for polyp detection.

Question 191: A patient with a suspected C-spine injury is brought to the radiology department. Which method of moving the patient's head and neck is appropriate?

Hyperextend the neck to open the airway
Log-roll the patient independently
Use a pillow for comfort and proceed
Manual in-line stabilization at all times (Correct answer)

Correct answer: Manual in-line stabilization at all times

Manual in-line stabilization of the cervical spine must be maintained at all times to prevent further injury until the injury is ruled out.

Question 192: What is the primary advantage of CT over conventional X-ray?

CT is cheaper
CT provides cross-sectional images with superior soft tissue contrast (Correct answer)
CT uses no radiation
CT takes less time

Correct answer: CT provides cross-sectional images with superior soft tissue contrast

CT provides detailed cross-sectional images with much better soft tissue contrast resolution than conventional X-rays, allowing visualization of subtle differences between tissues.

Question 193: Which of the following is required as proof of identity when a candidate checks in for the ARRT CT examination?

ARRT membership card only
Government-issued photo ID with signature (Correct answer)
Social Security card
Employer-issued badge

Correct answer: Government-issued photo ID with signature

Pearson VUE and ARRT require a valid, unexpired government-issued photo ID with a matching signature at check-in.

Question 194: Which factor related to ARRT CT certification most directly contributes to long-term job security for a radiologic technologist?

Employers cannot legally terminate certified employees
Certified technologists are more difficult to replace, increasing their value during staffing reductions (Correct answer)
ARRT monitors all employer actions against certified staff
Certification guarantees tenure after three years of employment

Correct answer: Certified technologists are more difficult to replace, increasing their value during staffing reductions

Certified specialists are harder to replace than generalists, making them more valuable to departments and more likely to be retained during organizational changes.

ARRT Computed Tomography (CT) Certification Examination

The ARRT CT certification exam assesses entry-level knowledge and cognitive skills required for computed tomography practice, covering patient care, radiation safety, image production, and CT imaging procedures across all major anatomical regions.

195

Questions

180 min

Time Limit

75%

To Pass

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